Head Titanium 5000, Prince Ti 500 or Prince Ti 200

No, I don't have more money: The Prince Ti 200 is the farthest I can go.
No, I don't have another choices: I got a 10% discount from a friend's father.
By the way, I don't have a racquet, so I need one as fast as possible

The Head and the Ti 200 are graphite, the Ti 500 is metal but I did like the feeling, and it's really cheap. The Ti 500 weighs 295+- and the other two weigh 275+-.

I'm a beginner and my style (in a year) should be a power hitter from baseline, going up to secure the point.

Get the Titanium 5000 -- it's a twin-tube graphite design based on the Ti Radicals. Very decent racquet, you shouldn't need to replace it any time soon, and it will play even better if you spend $5 to change the grip, maybe also get a custom string job at some point.